I mostly agree with you on the weapon / character customization part, so I will think about it.
Vehicles are also something I consider adding. In that case, I would probably add support for arbitrary terrain in the maps so that they can be vehicle-friendly. Lots of work to get it done, but will probably do it sometime.
Juggernaut level also seems a good idea but I will have to think it through thoroughly.
As for the CTF game, I thought the score was based on flag scores, and kills didn't count. Have you noticed something else? It may be a bug.
And yes, I should improve the jetpack graphics. Completely forgot about it. Thanks :)